Varied Temps Today Ahead Of Cold New Year's Eve

By Chris Spears

DENVER (CBS4) - Today's weather story involves a lesson in physics.

Seasonal air for late December is flowing into the state from the west and coming down the Rockies which is why the day started so much warmer in the foothills than it did in Denver.

Meanwhile, at the same time ... much colder air is moving into Colorado from the east. This sets up an inversion as seen in the picture below.

Since the cold air is shallow, dense and heavy (less than 2,000 feet thick) as it flows in from the east it stops at the foothills because it can't rise up in elevation.

The result is a crazy line with a wide temperature contrast right along the foothills and Interstate 25.

Because of this temps were all over today and varying as much as 10 to 20 degrees over a short distance. The higher you climb the warmer it will be and the lower you go the colder. The high at DIA was 38 degrees while Fort Collins and Greeley only made it to 18 degrees! At the same time Englewood, Highlands Ranch down to Castle Rock and Monument finished the day in the 50s and 60s!

Tonight a deeper batch of cold air will move in and it should keep us locked in the deep freeze all day tomorrow with highs only in the 20s. Patchy fog and flurries are possible tonight and Sunday.

If you are going to celebrate New Year's Eve with the Downtown Denver Fireworks it is going to be a cold one!

By the middle of next week we should warm back into the 40s.

Meteorologist Chris Spears travels weekly in the CBS4 Mobile Weather Lab reporting about Colorado's weather and climate. Check out his bio, connect with him on Facebook or follow him on Twitter @ChrisCBS4.